P.S. concerning your post about cultures/sub-cultures
The Belgians would be a sub-culture of the Celts.
If you want to do German sub-cultures, you have three consistent factions: Cherusci (Saxons), Suebi and Chatti (Hessians).
There is a theoretically fourth faction - in your time scale of 200BC - these are the left-Rhine Eburoni+two more.
They will be extinct by Caesar in 50 BC and on their empty land, the Franks will rise from the moment the other three faction will be out of power and take on the Saxons and the Allemanns (aka Suebi).
The Franks are all the small tribes that were pro Roman and moved because of confrontations with the bigger alliances into western Europe. That is why it is called the Rhine-Weser Franks.
This is the Roman/German blend zone. But 200 BC this would be home of Eburoni etc. - we do not know how they called their federation or themselves.
By findings they are today referred to Celts, but for the Romans they have been Germans and later Germans moved into their territory.
It depends now which thesis you would like to apply by what is a Celt and what is a German.
They took one legion from the Romans, that's why they got extinct. So that has been some bigger player, that stood there and was able to hold their ground against other tribes.